@BonsaiWilderness
You are in the USA, the slippery elm, Ulmus rubrum, is native and fairly common. The field maple, Ulmus minor, is native to Europe. The field maple is an invasive species in some areas. You need to use a dichotomous key to definitively sort out which is which. Keys are usually available as links to your state forestry websites. Browse your state forestry website and look for Keys to identifying trees of your state. Given you found it in "woods", even second growth forest, the probability is that it is Ulmus rubrum, as its seedlings tolerate more shade than many other elm species. So I'd say better than 50% chance you have slippery elm.
Slippery elm and field elm make good bonsai. Actually, virtually all elm species make good bonsai. This is a very young seedling, as such it is silly putty as bonsai, can be bent and twisted into any style you like. It will need a fair amount of growing to get any trunk caliper. You are probably looking at 5 to 10 years before it is "exhibition ready".
In the future, you should look for large diameter trunks of the same species. Look for trunks that are 2 inches or larger in diameter. These will likely be over 5 feet tall, key is that there are bends and twists in the first 6 inches of the trunk. If the first 6 inches of a trunk is interesting, then the tall tree can be cut short, and new branches can be trained to develop the whole tree. Truth is, most bonsai are brought DOWN to size by bonsai training. Key is to learn to see a large tree, and figure out how to bring it down to size, rather than grow a small seedling up to the size of your desired plan.
In fact, when you grow bonsai from seed, often you have to let the seedling to get to large size, 5 to 15 feet tall, and then cut it back down to 4 or 6 or 8 inches. The height is needed to get the diameter of trunk needed to create the image of a large tree in miniature. So even bonsai from seed, tend to spend 5 or more years at a size and height that is as much as 10 times the desired finished height.
It takes a bit to get to see the small tree in the 10 foot tall tree. But eventually you will get "the eye". Learn to identify the trees in your woods. You should be able to walk through and identify at least half the trees in there. You will then be able to read and recognize which species you have that are good for bonsai.
Look for
Hornbeam, loose flowered hornbeam also called American hornbeam, Carpinus caroliniana. Its great for bonsai. Similar but with slightly different bark, is Hop-Flowered hornbeam, Ostrya virginiana. It grows in slightly dryer sites than Carpinus, It too is excellent for bonsai.
Look for Acer rubrum - red maple, is reasonably good for medium to large scale bonsai. Most of the Eastern North American maples are not good for bonsai. Silver maple, Acer saccharinum, is poor, Acer negundo - box elder is poor choice, and sugar maple, Acer saccharum is also a poor choice for bonsai. The man made hybrid, Acer x freemanii sold under many names as a street tree is somewhat more difficult to use as Acer rubrum, but it is not impossible.
Beech, Fagus grandifolia is tricky, but desirable for bonsai. It is difficult to grow and requires some specialized pruning techniques, but a well grown beech bonsai is glorious.
As said earlier all the elms, are good for bonsai. Even the American elm, the leaves reduce nicely.
Linden - Tilia americana has large leaves that do not reduce beyond about 1 to 2 inches, it is sometimes used for large scale, 3 to 4 foot bonsai. It can be impressive as bonsai.
Crataegus - the hawthorns - all species make good bonsai. Sorting out species identity is tricky if you live in an area with more than one species, as they hybridize frequently.
Malus - the apple tree, and crab apple trees, if you have any that have "gone native", they make good bonsai.
Shrubs to look at, holly, especially any of the native hollies, like Ilex opaca, Ilex glabra, Ilex verticillata and the many other species, these all make good bonsai. Amelanchier, serviceberry, or saskatoon, also called shadblow, this cousin of the apple is an excellent tree for small bonsai as it does not trunk up quickly.
Juniper communis - the field juniper is good. Juniperus virginiana - the eastern red cedar is not so good.
Eastern white pine, Pinus strobus - is a poor choice for bonsai. Pinus virginiana, and Pinus rigida - the Virginia pine, and the Pitch pines are good for bonsai. The long needled yellow pines of various species are poor choices. Pines need to have needles naturally less than 5 inches or they are not worth trying to do bonsai with them.
If you are lucky enough to have American persimmon, Diospyros virginiana, I believe it will make excellent bonsai. They develop the coolest, near black, alligator checked bark, and bark starts forming on trees as young as 10 years old. This one you might have to do from seed, start a bunch, as you need both a male and a female to get fruit.
SO if you learn to identify each of the trees I just listed, you will probably cover half the trees in your woods.
A few bad choices, Fraxinus - all the North American ash species, are poor choices. Walnut, pecan and butternut are poor choices. Hickories - the leaves never reduce, thus making them poor choices. Birch are used by some, they are tricky, often results are not as good as the "idea".
This should get you started. Get a "Trees of North America" guide, or Trees of Eastern North America. Also browse your State Forests websites. Learn your local trees and shrubs.